Elecraft

Quick sanity check on filter test

Classic

List

Threaded

3 messages Options

Jim AB3CV

Quick sanity check on filter test

I've long suspected the 250hz8p filter in my sub was not working correctly.

I finally took it out of the sub and placed in in the main next to another
250hz8p and set the suspect filter to kick in at 700hz and the good one to
kick in at 600hz.

I then input a test signal using a XG2 and dialed down the bandwidth from
2.8khz down through the 700 and 600 filter set points. AGC set to off.

The "good" one still requires an 8db boost to stay close to the 2.8Khz
filter in amplitude. The suspect one is *way* past that. Even if I lower
the boost on the good one to 0db boost and boost the suspect one by 8db
they still aren't close. Probably another 8-10db difference.

This is consistent with what I was seeing in the subrx vs main but by
placing the filter in a main socket I could eliminate the subrx as the
source of the problem.

Anyone else had a bad 8 pole?

I'd like some feedback on this test method to make sure I've got my ducks
in a row before getting another filter to replace this one.

Thanks

Jim ab3cv
______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html

Arie Kleingeld PA3A-2

Re: Quick sanity check on filter test

I once had a bad xtal filter in my FT1kMP.
It was visible on the s-meter when switching between different BW's. The
filtering itself was still OK but there was some attenuation (at least
an S-point or so). Could not measure this with the trx itself (a big
hurray for the K3 that it can) but I used a signal generator and scope
to check it.

I replaced the filter and all was up to spec again. So it happens.

The dBV meter of the K3 is a nice measurement system. I have used it
several times to checkout some filtering and signal splitting networks
in combo with a signal generator.

73
Arie PA3A

Op 31-5-2013 3:24, Jim Miller schreef:

> I've long suspected the 250hz8p filter in my sub was not working correctly.
>
>
> Anyone else had a bad 8 pole?
>
> I'd like some feedback on this test method to make sure I've got my ducks
> in a row before getting another filter to replace this one.
>
> Thanks
>
> Jim ab3cv
>

______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html

Jim AB3CV

Re: Quick sanity check on filter test

In reply to this post by Jim AB3CV

Just a quick follow up. Spoke to Howard at Elecraft support and a
replacement is in the mail!

Outstanding products backed by outstanding service!

73

jim ab3cv (happy clam!)

On Thu, May 30, 2013 at 9:24 PM, Jim Miller <[hidden email]> wrote:

> I've long suspected the 250hz8p filter in my sub was not working correctly.
>
> I finally took it out of the sub and placed in in the main next to another
> 250hz8p and set the suspect filter to kick in at 700hz and the good one to
> kick in at 600hz.
>
> I then input a test signal using a XG2 and dialed down the bandwidth from
> 2.8khz down through the 700 and 600 filter set points. AGC set to off.
>
> The "good" one still requires an 8db boost to stay close to the 2.8Khz
> filter in amplitude. The suspect one is *way* past that. Even if I lower
> the boost on the good one to 0db boost and boost the suspect one by 8db
> they still aren't close. Probably another 8-10db difference.
>
> This is consistent with what I was seeing in the subrx vs main but by
> placing the filter in a main socket I could eliminate the subrx as the
> source of the problem.
>
> Anyone else had a bad 8 pole?
>
> I'd like some feedback on this test method to make sure I've got my ducks
> in a row before getting another filter to replace this one.
>
> Thanks
>
> Jim ab3cv
>